An influential committee of MPs is to investigate fears that large numbers of UK troops who have served in Iraq and Afghanistan are at risk of brain damage after being exposed to high-powered explosions.

Last week the Guardian reported that the Ministry of Defence has launched a major study into mild traumatic brain injury (mTBI) in soldiers returning from active service. Yesterday, James Arbuthnot, chairman of the defence select committee, said it would be investigating the issue as part of its ongoing inquiry into medical care for service personnel. "The committee has decided that this is a significant issue which deserves proper scrutiny," he told the Guardian. "We are therefore writing to the MoD to get its response to the issues raised and will question ministers when they come before the committee later this year."

The focus on mTBI, which can lead to memory loss, depression and anxiety, follows growing concern in the US, where the condition has been named as one of four "signature injuries" of the Iraq war.

Yesterday Liam Fox, the Conservative defence spokesman, welcomed the defence select committee's decision to investigate the possible impact of mTBI but criticised the government for its response. "I think they have been very slow to address what is a well documented problem," he said.

Dr Fox said he had raised the issue repeatedly after returning from a fact-finding mission to the US at the beginning of the year: "Despite this, we have been unacceptably slow to act and the longer we take to deal with it, the more people are likely to suffer long-term problems."

The US army says as many as 20% of its soldiers and marines may be at risk of mTBI from blows to the head or shockwaves caused by explosions. It is introducing a large-scale screening programme for troops returning from the frontline. In the UK, defence officials have been reluctant to follow the US lead, arguing that the science is inconclusive and that the US and UK experience has been different.

A spokesman for the MoD said: "It is a very complex area. We have no way of knowing whether [the US assessment] is accurate because there is a level of dispute as to what constitutes mTBI."

However, the MoD is introducing a series of measures - including a comprehensive screening process, a telephone helpline and a website - to deal with what could be a 20-fold increase in troops with mTBI. Kit Malia, a cognitive rehabilitation therapist, who will oversee the MoD's programme, told the Guardian: "If the American figures are correct, this is massive, absolutely massive."